Lifting jack



A. H. JOHNSON V w LIFTING JACK Filed March 22. 1926 a 3,7? I M Z0 2 fin 'l INVENTOR A1 {red H. Johnson Patented Apr. 17, 1928.

UNITED STATES PATENT OFFICE.

ALFRED H. JOHNSON, OF NILES, MICHIGAN, ASSIGNOR TO NATIONAL STANDARD COMPANY, OF NILES, MICHIGAN.

fir-TING JACK.

Application filed March 22, 1926. Serial No. 96,556.

The main object of this invention is to provide an improved lifting jack of the screw type which ma be extended to a considerable height an at the same time is very compact when collapsed.

A further object is to provide an improved lifting jack having a plurality of screws which is simple and economical and at the same time very durable in structure.

Objects pertaining to details and economies of my invention will definitely appear from the detailed description to follow. The invention is clearly defined and pointed out in the claims.

A structure embod ing the features of my invention is clearly i lustrated in the accompanying drawing forming a part of this application, in which: 7

Fig. 1 is aside elevation of a lifting jack 2o embodying the features of my invention.

Fig. 2 is a vertical section on a line corresponding to line 2-2 of Fig. 1, certain parts full lines for convenience in being shown in illustration.

In the embodiment illustrated, I provide a standard 1 having a base or foot 2, the standard having a longitudinal cylindrical bore 3. At its upper end the standard has a yoke-like bracket 4 carrying a collar-like part spaced from the upper end of the standard. The externally threaded tubular lifting member 6 is arranged within the bore of the standard and through this collar 5. Y

The driving nut 7 is arranged between 5 the bracket and the upper end of the standard, a ball thrust bearing designatedgenerally by the numeral 8 being arranged between the nut and the standard and supporting the load on the nut. This nut 7 is provided with a beveled gear 9 which is in mesh with the driving pinion 10 supported in a bearing 11 on the bracket. This pinion is provided with a socket 12 adapted to receive the driving crank.

At its upper end the standard is provided with a pair of opposed boss-like tubular holders 13 disposed transversely relative to the bracket. Friction blocks or shoes 14 are arranged within the holders and are yieldiiigly urged against the lifting member 6 by means of the springs 15.

The adjustable thrust member 16 is threaded into the outer ends of the bosses for supporting and regulating the tension on w the springs. A second lifting screw 17 has threaded engagement with the internally threaded part 18 at the upper end of the lifting member6. The friction shoes are adaptedto frictionally hold the members 6 against rotation so that as the nut is rotated the lifting member is raised and lowered. A stop 19 is provided at the upper end to limit the lowering movement of the lifting mem-- her and an unthreaded part 20 at its lower end limits the upward travel thereof. When these sto )S arein engaging position the lifting mem er 6 turns with the nut, and when the head 21 engages the work the member 17-1s held against rotation, the rotation of the member 6 acting as a nut to drive the same. a

My improved lifting jack is very simple and economical in itsparts and at the same time is strong and durable and not likely to be injured or broken in use.

Having thus described my invention what I claim as new and desire to secure by Let-- ters Patent is:

1. In a lifting jack, a standard having a longitudinal bore, said standard being provided with a friction shoe holder opening to said bore, a nut rotatably mounted on the top of said standard, means for driving said nut, a tubular cylindrical lifting member disposed in said standard and having an external unbroken threadcoacting with said nut, said lifting member being provided with means limiting its travel, a spring pressed friction-shoe in said holder coacting with the cylindrical threaded surface of said lifting member and radially disposed relative thereto, and a second lifting member threaded into said tubular lifting member and provided with a work engagin head.

2. In a lifting jack, a stan ard having a longitudinal bore, said standard being provided with a friction shoe holderopening to said bore, a nut rotatably mounted on the top of said standard, means for driving said nut, a cylindrical lifting member diso posed in said standard" and having an external unbroken thread coacting with said nut, said. lifting member being provided with means limiting its travel, and a spring pressed friction shoe in said holder coacting with the cylindrical threaded surface of said lifting member and radially disposed rela tive thereto.

3. In a lifting jack, the combination of a standard provided with. a cylindrical bore, no

a nut mounted on said standard, a tubular cal threaded surface thereof, and a second cylindrical lifting member disposed in said lifting member threaded into said tubular standard and having an external unbroken lifting member and provided with a. work i thread 'coacting with said nut, a spring en aging head.

5 pressed friction member mounted in said 11 witness whereof I have hereunto set standard radially relative to said lifting my hand. 7 member and coacting with the said cylindn- ALFRED H. JOHNSON. 

